This is actually a pretty common scenario, where you have three components:
- A cluster of stateless web servers that maintain open connections with all clients (load balanced across the cluster, obviously)
- A persistent main data storage - Neo4j in your case
- A messaging/queueing backend for broadcasting messages across channels (thus across the server cluster) - Redis
Your requirement is for new clients to receive an initial feed of the recent messages, and any consequent messages in real-time. All of this is implemented in your connection handlers.
Essentially, this is what your (pseudo-)code should look like:
class ConnectionHandler:
redis = redis.get_connection()
def on_init():
self.send("hello, here are all the recent messages")
recent_msgs = fetch_msgs_from_neo4j()
self.send(recent_msgs)
redis.add_listener(on_msg)
self.send("now listening on new messages")
def on_msg(msg):
self.send("new message: ")
self.send(msg)
The exact implementation really depends on your environment, but this is the general flow of things.